fix Vue demo

Author: smnandre

ux.symfony.com/templates/ux_packages/vue.html.twig

@@ -20,14 +20,15 @@
 {% endblock %}
 
 {% block code_block_left %}
-    <twig:CodeBlock filename="templates/ux_packages/vue.html.twig" height="350px"/>
+    <twig:CodeBlock filename="assets/vue/controllers/PackageSearch.js" height="300px" />
 {% endblock %}
 
 {% block code_block_right %}
-    <twig:CodeBlock
-        filename="assets/vue/controllers/PackageSearch.js"
+    <twig:CodeBlock 
+        filename="templates/ux_packages/vue.html.twig" 
         height="350px"
         language="html"
+        targetTwigBlock="demo_content"
     />
 {% endblock %}